<p>Energy storage dielectrics, such as relaxors, relaxor antiferroelectrics and paraelectrics have attracted extensive attention for pulsed-power devices owing to their high power density, fast charge–discharge rate, and good cycling stability. However, simultaneously enhancing the maximum polarization and the dielectric breakdown strength remains challenging. To address this issue, A-site and B-site vacancy compensation were respectively constructed in a weakly polar CaTiO₃ matrix, thereby achieving a synergistic optimization of the maximum polarization and dielectric breakdown strength while elucidating the mechanism by which the defect configuration governs the polarization response. XPS results demonstrate that charge compensation for defects is realized via cation vacancies rather than the reduction of Ti⁴⁺. Rietveld refinement confirms that all compositions form single phase orthorhombic solid solutions. Nevertheless, the stronger distortion of the oxygen octahedral framework and the local bond length asymmetry induced by B-site compensation endow it with a high dipole moment. Moreover, the dielectric breakdown strength of the system does not follow the conventional inverse grain size relationship but is instead jointly governed by the defect chemistry and densification dictated by the compensation route. Under the combined effect of these factors, the B-site-compensated ceramic attains a breakdown field of ~ 80&#xa0;kV/mm and a maximum polarization of ~ 16 μC/cm², thereby delivering a recoverable energy storage density of 5.67&#xa0;J/cm³ and an efficiency of 93%, along with favorable pulsed charge–discharge characteristics. This work highlights the distinct influences of the compensation route and defect type on the polarization response and dielectric breakdown strength of weakly polar dielectrics, and reaffirms the effectiveness of defect engineering for developing high-power weakly polar energy storage dielectric materials.</p>